High frequency oscillation system



P 1938. e. c. SOUTHWORTH 2,129,713

HIGH FREQUENCY OSCILLATION SYSTEM AND METHOD Filed 001;. 9, 1954 3 Sheets-Sheet l L i 11;} c

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INVENTOR ATTORNEY Sept. 13, 1938. s. c. SOUTHWORTH 2,129,713

HIGH FREQUENCY OSCILLATION SYSTEM AND METHOD Filed 001,. 9, 19-34 3 Sheets-Sheet 2 May/zetastatdc Field i Q] Flute Cal-rem:

INVENTOR Q2 5.6" Southwmah BY W ATTORNEY Sept. 13, 1938. a. c. SOUTHWORTH HIGH FREQUENCY OSCILLATION SYSTEM AND METHOD Filed Oct. 9, 1934 3 Sheets-Sheet 3 INVENTOR G. C. 50 at/awol llk/ BY ATTORNEY Patented Sept. 13, 1938 UNITED STATES PATENT OFFICE HIGH FREQUENCY OSCILLATION SYSTEM AND METHOD Application October 9.

29 Claims.

A principal object of my invention is to provide for the generation of high frequency alternating currents for the propagation of electric waves from one place to another. The alternating our- :1 rents referred to may be conduction currents, or displacement currents in a dielectric. or both. Another object is to provide improved electron discharge apparatus for use wherever such apparatus may be of advantage. A more special ob- 10 ject of my invention is to provide for the generation of displacement currents to be propagated as electromagnetic waves in dielectric guides. Another object is to provide oscillation generators in operative combination with respective dition is to provide a suitable design and dimensions of the associated guide and generator so that a desired frequency will be generated. An-'- other object is to provide a high frequency oscillation generator in combination with a dielectric guide so that waves of a desired type will be propagated. Another object is to accomplish some or all of the foregoing objects by causing electrons to oscillate in suitable paths. so that 5 the desired waves will be generated in the lines of force which extend therefrom. Another object is to combine an oscillation generator with a dielectric guide and a reflector so that the period of waves in the guide as determined by the refiector will enforce a corresponding period on the generator. In some cases my invention may be realized by the use of vacuum tubes built in combination with such guides; in other cases spark gap oscillators may be built in combination with such guides.

All the foregoing objects and aspects of my invention, and other objects and advantages thereof, will be made apparent in the following specification in which I disclose a limited number of examples of practice according to the invention. The following specification has relation more particularly to these particular examples ,of the invention, and its scope will be indicated in the appended claims.

Referring to the drawings. Figures 1 and la are diagrammatic longitudinal and transverse sections of a metal-sheath air-core dielectric guide showing the electric and magnetic lines of force for symmetric electric waves therein; Figs. 2 and 2a are such sections for symmetric magnetic waves; Figs. 3 and 3a are such sections for asymmetric electric waves; Figs. 4 and 4a are such sections for asymmetric magnetic waves; Fig. 5 is a diagram showing electromagnetic waves as generated by the oscillation of an electron; Fig.

electric guides. A further object in this connec 1934, Serial No. 747,605

is a diagram showing such waves as generated by the oscillation of two opposite charges in opposite phase; Fig. 7 is a diagram showing the waves generated by opposite charges oscillating in opposite phase along paths which are arcs of a circle; Fig. 8 is a longitudinal section of a combined dielectric guide and three-electrode tube for the generation of symmetric electric waves; Figs. 9, 9a and 10 are respectively two cross-sections and a longitudinal section of a combined 10 dielectric guide and three-electrode tube for the generation of asymmetric electric waves; Fig. 11

is a longitudinal section of a combined guide and two-electrode tube for generating and propagating symmetric magnetic waves; Fig. 12 is a detall cross-section of the same; Fig. 13 is a curve diagram exhibiting a certain quantitative relation involved in the operation of this apparatus; Fig. 14 is a longitudinal section of apparatus somewhat like Fig. 11, but with three electrodes instead of two; Fig. 15 is an enlarged cross-section of the same apparatus; Fig. 16 is a corresponding cross-section showing a modification; Fig. 17 is a or -section of the vacuum tube part of apparatus or generating and propagating asymmetric magnetic waves; Fig. 18 is a crosssection showing a sieve for purifying the waves generated by the apparatus of Fig. 17; .Fig. 19

is a longitudinal section of a combined dielectric guide and spark gap for the generation and propagation of symmetric electric waves; Fig. 20 shows a modification for the same purpose; Fig.

21 is a longitudinal section of spark gap apparatus for asymmetric electric waves; Fig. 22 is a cross-section of the same; Figs. 23 and 24 are respectively longitudinal section. and cross-section of spark gap apparatus for asymmetric magnetic waves; Fig. 25 is a longitudinal section of apparatus for symmetric magnetic waves; Fig.

26 is a perspective of a detail part thereof; and Fig. 27 is a simplified diagrammatic cross-section.

The nature of the electric waves in a dielectric guide depends somewhat on the shape of the cross-section of the guide. For the sake of definiteness, the examples of the invention here to be described will involve guides of circular crosssection. A dielectric guide may or may not be metal sheathed, but in the examples of the invention to be shown here, metal sheathed guides 5 will be represented. In any case, a dielectric guide from one place to another place is a body of dielectric extending continuously from the one place to the other and bounded laterally by a dielectric discontinuity. There are various types electric (E1), and asymmetric magnetic (H1).

These various types are designated as electric or magnetic according as they have their principal components of electric or magnetic force in the direction of propagation, and they are symmetric or asymmetric according as the lines of force are or are not symmetrically disposed about the guide axis. In the case of asymmetric waves, the term will here be restricted to waves whose lines of force having components in the direction of propagation are all approximately symmetric to a single plane containing the axis of the guide, but the plane not intersected by any of those lines. These four types of waves are shown in Figs. 1, 1a, 2, 2a, 3, 3a., 4 and 4a, in which the continuous lines represent lines of, electric force and the dotted lines represent lines of magnetic force. In all these figures a metal sheathed guide is shown. The sheath or shell would actually be relatively much thinner than indicated. The lines of electric force in the dielectric core correspond to displacement currents", but when they are continued in the conductive shell, they link through electrons and protons in alternation and correspond to conduction currents. At the very high frequencies considered, both electric and magnetic lines in the shell will lie very close to its inner surface, but the shell is shown thick so the lines therein can be represented clearly.

In many of the devices disclosed hereinafter, certain electrons in a vacuum 'tube are constrained to oscillate in definite patterns, and we can look upon the waves in the guide as traveling wave shapes in the lines of force which proceed directly from those electrons, or as resultants obtained by combining such shapes in various lines of force.

4 An electron at rest may be regarded as having Going on, when the electron gets back to B the initial line of force AD will have become BCaBsAsD. It is easy to visualize the ultimate shape of the line of force after many such oscillations; it'will lie between two hyperbolas whose asymptotes are BB4 and BB2B3B4. At any one instant, there will be this wavy line of force lying between hyperbolas diverging to the right; and as time progresses, these waves in the line will progress to the right.

If a group of electrons and an equal positive charge oscillate in opposite phase with simple harmonic motion over the line ABC in Fig. 5, their lines of force will compound to give resultant waves as shown in Fig. 6.

If electrons oscillate with simple harmonic motion along arcs of the circle seen in perspective at ABCB' in Fig. 7, and if equal positive charges the resultant wave will consist of transverse circular lines of force progressing to the right. In the waves of Fig. 6 the lines of electric force have components in the direction of propagation; therefore they are electric waves. The lines of magnetic force in Fig. 6 are circles, all centered at the mean point of the said electrons and positive charges, and perpendicular to the plane of the paper and have no components in the direction of propagation. In Fig. 7 the lines of electric force are in circles perpendicular to the direction of propagation, and the lines of magnetic force have components along the direction of propagation; accordingly, the waves of Fig. 7 are magnetic waves.

Referring to Fig. 8, this shows a longitudinal section of a dielectric guide having a metallic cylindrical shell 3 enclosing an air core I and extending indefinitely to the right. Near the axis of this shell lies an electron-emitting filamentcathode 5. Surrounding this cathode 5 is the cylindrical plate electrode I, conductively connected with shell 3 at 8. The space is evacuated with in the cylindrical metal wall I and the glass end walls or seals 9 at the right and 9' at the left Surrounding the cathode 5 within the plate electrode l is thecoaxial cylindrical grid 6.

An inner coaxial cylinder 2 lies at the left with its right end tapered and extending into the corresponding end of the grid 6. The end of this inner tube 2 and the end of the grid 6 lap past each other with a segment of the glass seal 9 between them, but with conductive connections through the glass seal, as indicated by the reference numeral I. The plate electrode l and the grid 6 serve as a concentric conductor system in continuation with the system 32, having the same ratio of outer and inner radii and therefore the same characteristic impedance.

Lying transversely across the annular space between the part 3' of the shell 3 and the inner 40 coaxial shell 2 is a metallic of two parts 4 and 4' with an insulating layer 4" between them. It will readily be seen that the shell 3' and the inner shell 2 are insulated from each other for direct currents though virtually they are conductively connected through 4 and 4 for high frequency alternating currents.

Relatively to the cathode-filament 5, the grid reflector consisting 6 is strongly positive and the surrounding plate,

I is negative. Many electrons from the cathode 5 are accelerated in radial paths to the grid and 5 pass through its openings but are reversed by the strongly negative plate I. Thus such electrons may oscillate in radial paths through the openings of the grid 6 several times before they are captured by the grid. Such an electron, subject to forces which tend to bring it back to a mean position, may be said to be subject to an equilibrium field. Any such electron oscillating along a radial path has waving lines of force extending right and left therefrom, such as pictured in Fig. 5. Between the axis of the tube 3 and the upper section of that tube shown in Fig. 8 there will be a train of waves extending to the right like those shown in Fig. 6. Similarly, there will be such a train below the axis and extending to the right. Likewise, there will be such wave trains on each side of the axis in any plane containing the axis.

The waves progressing to the leftin the annular space between the cylindrical shells 3' and 2 are represented by radial lines of forceso that said shells 3' and 2 constitute the two conductors of a concentric conductor system along which transmission takes place fromright to left. The

waves transmitted in this way are reflected by 7 the refiector'4- 4' and proceed thence from left to right along the concentric conductor system, whose two conductors are '3' and 2 merging respectively into the members I and 6. The ad- Justments of electromotive forces and of dimensions, especially the longitudinal adjustment of the reflector 4-4', are made and related so that when the reflected waves arrive at the grid Ii, their lines of force are in the same direction as the motion of the respective electrons from which they originated. Thus the oscillatory frequency of the electrons is enforced by the period of the wave travel therefrom to the reflector 4-4' and back. The adjustable reflector 4-4' serves not only to return the reflected wave in proper phase,

but to get a relation of the elements involved that is most suitable for efllcient operation.

The circuits of the three-electrode vacuum tube I9-9' are shown schematicallyat the left of Fig. 8. The tubular member 2 serves as grid power lead and as a shield for the filament leads against high frequency alternating cur rents.

The characteristic impedance of' the concentric conductor system 3'-2 is given by the formula z=13a.2 logmR/r (1) in which R and r are the outer and inner radii of the concentric conductor system. A conven ient practicable value for this impedance is 20 ohms; it follows from the formula that the corresponding ratio of the two radii should be 1.4. The characteristic impedance of the dielectric guide 3--'| extending to the right should match the characteristic impedance of the concentric conductor system on the left. The formula for the characteristic impedance of a metal-sheathed air-core dielectric guide for symmetric electric waves is given by the formula in which I is the frequency of the waves and i is the critical or limiting frequency of transmission through such a guide. The critical frequency fc, expressed in megacycles, is related to the guide radius by the formula fc=11,450/R (3) The radius R of the dielectric guide at the right is the same as the outer radius of the concentric conductor system. A convenient value to be assigned for the frequency f is 3x10 cycles per second. This determines the critical frequency according to Formula 2, assuming the same characteristic impedance, 20 ohms. Then, by Formula 3, the minimum radius R for guided wave transmission is determined and is found to be about centimeters.

As shown and described in connection with Fig. 8, the system is adapted for the generation and propagation of electromagnetic waves in a dielectric guide; more particularly, the waves are of symmetric electric type and theguide has a metal shell with an air core. If it is desired to generate and propagate electric waves in a normal concentric conductor system, this can be accomplished by a simple modification of Fig. 8 which consists merely in removing the annular reflector 4-4 and placing a complete disc reflector across the tube 3 at the proper distance on the right of the vacuum tube I-99'. In this case the dielectric waves entering the guide 3 at the right will be reflected back and reenforce the electric current waves with radial lines of force which will progress indefinitely to the left I placement waves.

along the concentric conductor system 3-2. It will readily be seen that whether the waves are to be propagated on one side as 'waves In a concentric conductor system 'or as waves in a dielectric guide, they may be reflected on the opposite side with their energy in either form.

Fig. 9 is a diagrammatic cross-section and Fig. is a corresponding longitudinal section of a combined dielectric guide and three-electrode vacuum tube source for the generation and propagation of asymmetric electric waves within the guide. The filament-cathode 5 comprises two parts on opposite sides of the guide axis and parallel therewith. Around each part of the cathode is a grid 6 having its cross-section D-shaped, with rounded corners as shown in Fig. 9. PlaQ ddiametricallyis-a metallic "septum 20 between the two grids, dividing the interior of the shell 3 into two half cylinders.

Referring to Fig. 3a, it will be seen that in the asymmetric electric wave the equipotential surfaces, indicated by dotted lines, are D-shaped with rounded corners; the grids 5 of Figs. 9 and,

10 are shaped approximately to follow such an equipotential surface. A tolerable approximation would be attained if the grids were of circular cross-section. Also, the septum 20 lies in an equipotential surface.

The grid 6 is positive, and the plate electrode consisting of the shell 3 and the septum 20 is negative, so that the electrons from the cathode 5 oscillate through the grid along the lines of force such as shown in Fig. 3a, and generate the corresponding type of electromagnetic dis- These waves are propagated from the generator both ways along the tube 3. One way, they are reflected at 34 according to the principles explained in connection with reflector 4 in Fig. 8.

On the opposite side from the reflector 24 is the screen of wires 2I shown in Figs. 9a and 10, which lies in great part across the electric lines of force of the wave. This screen 2i absorbs components in other directions than across its wires, acting as a sieve to purify the waves to the asymmetric electric type.

The septum 20 is not a necessary element and may be omitted, or it may be retained and only one filament and its corresponding grid be employed at one side, those parts shown, on the other side in Figs. 9 and 10 being omitted.

The combined structure of dielectric guide and two-electrode vacuum tube shown in longitudinal section in Fig. 11 is adapted for the generation and propagation of symmetric magnetic waves. Within the cylindrical metal anode I is an axial cathode 5, both comprised in the power circuit havingthe battery 4|. Glass end seals 9 and 9' are provided, and the space between them and within the anode I is evacuated. At its ends the tubular anode I has flaring conical extensions 42 which connect with the cylindrical shells 3 and 3' respectively. Surrounding the anode I are the core 43 and the winding 44 of an electromagnet, which has axial symmetry with respect to the cathode 5. A direct current through this winding 44 obviously establishes a strong magnetostatic field having longitudinal lines of force within the anode I and around the cathode 5.

In the absence of the fleld due to the winding 44 the electron discharge from the cathode 5 to the anode I would be along radial lines. The presence of this field causes a deflection of the electrons. With a comparatively weak fleld an electron path may be as at 45 in the cross-section tive.

-- across the cathode 6 and the anode I.

a path as at 46, and a yet stronger field may deflect the electrons so that they will not arrive at the anode I but will be constrained to return in a circuit to the cathode 6, as indicated at 41. The volume of current from the cathode'l to the anode I will be only slightly affected by increasing the strength of the field due .to the winding 44, if this merely changes the electron tra- Jectories from the shape at 46 to that at 44'. But a change as from 46 to 41 gives a decided change in the volume of current. Accordingly, a plot of the current against the strength of field due to the winding 44 has the shape shown in Fig. 13. An adjustment at or near the knee of this curve is the best for the development of suitable oscillatory operation.

There is'an adjustable reflector 34 at the left of Fig. 11. Any irregularity in the discharge from the cathode 5 to the anode l generates a wave which "travels to the left, existing as a dielectric displacement current wave within the shell 3; this wave goes to the reflector 34, thence back to its source, where it momentarily enhances the discharge current. Thus, in somewhat the manner described heretoforeinpther cases, the period of the to-and-fro wave on the left stabilizes the frequency of an oscillatory discharge orresponding electromagnetic waves are generated and sent out along the dielectric guide 3 to the right. These waves have their origin in electronic oscillations along paths such as 41 in Fig. 12. It will readily be seen that as lines of force these paths combine to give a resultant having a substantial circular component, coaxial with the axial cathode 5. There is a screen of radial wires at 48 which purifies the waves through it to bring them to the symmetric magnetic type. Beyond this screen 48 is an adjustable iris 49 for volume control. Thus the waves sent along the dielectric guide having the shell 3 have their lines of electric force as shown in Figs. 2 and 2a and are symmetric magnetic waves.

In .the modification shown in Fig. 14, a cylindrical, coaxial grid 6 is introduced. This is made positive and the plate electrode I is made nega- The magnetostatic field indicated by the arrow 50 is present, the same as in Fig. 11. Without this field, the electron paths and the lines of force would be as in the cross-section shown in Fig. 15. With this field, the electron paths are given a tangential component in the region between the cathode and the grid. Many of them pass into the space between the grid and the plate, where they are given a tangential acceleration favorable for generating waves with a large component of the symmetric magnetic type.

In the modification indicated by the cross? section of Fig. 16, the coaxial cylindrical grid of Figs. 14 and 15 is replaced by a plurality of plane radial grids 6'. These are positively charged. Their edges nearest the filament provide an accelerating electrostatic field which. in conjunction with the magnetostatic field such as indicated by the arrow 56 in Fig. 14, gives to the electrons a motion with a substantial tangential component. The outer parts of the grids 6' of Fig. 16 enforce further tangential acceleration of the electrons passing through their meshes.' It will be noticed that these radially disposed grids 6' in Fig. 16 lie in equipotential surfaces of the symmetric magnetic type of wave, and therefore they do'not interfere with the regular transmission of such a wave.

2,129,718 shown in Fig. 12. A stronger field will give such One way to obtain theasymmetric magnetic type of wave is to make the imposed magnetostatic field asymmetric with respect to the axis rathefthan symmetric as was done in Hg. 11. An electromagnet with suitably directed cores and air gaps may be provided for-this purpose, but a special construction is shown in cross-section in Fig. 17. This is similar to Fig. 11, except for the principal distinction that the magnet core 43 and winding 44 have Fig. 17 two large conductors 46 and 46' have been connected at diametrically opposite points of the anode shell I. A current of low voltage but high amperage is sent through the circuit of these two conductors. The lines of current flow in this circuit split from the conductor 46', halt going around one side of the shell I and half around the other side to unite in the conductor 46'. This large current establishes an interlinked magnetostatic field of considerable magnitude. As viewed in Fig. 17, the lines of magnetic force go away from the observer in the region marked 6| and come toward the observer in the region marked 62.

With such a fleld, the electrons from the cathbeen removed and in- ..ode,6 a re deflected from their normal radial.

travel toward the plate I and are constrained to travel along lines such as indicated in Fig. 17. It will be' apparent from this figure that the lines of force of the electric waves have a substantial component parallel with the plane of the tube axis and the axis of the two conductors 46 and 49'. This wave may be reflected on one side and propagated according to the same general plan disclosed for earlier figures. It may be purifled to the desired asymmetric magnetic type by a sieve like that indicated at 2| in Fig. 18.

It will be seen that in the foregoing disclosures, to a great extent, a desired type of electromagnetic wave has been established by constraining electrons to oscillate along paths which are the lines of electric force of the desired waves. In the foregoing cases these constrained electron paths have been established within vacuum tubes by means of suitable electric and/or magnetic fields imposed upon the spaces within those tubes. But a suitable constraint may be imposed on the electrons by other means.

vAt the ends of the aligning cylindrical conductors 6| and 62 of Fig. 19 are the opposite spherical knobs 63 and 64. This system is axially disposed in the guide shell 3. An intermittent spark discharge is maintained across the gap 63-64 by means of the associated direct current power circuit 65. The lines of force of the oscillatory spark gap discharge are whipped oflf and closed into loops, which are propagated right and left. Those going to the left are reflected by the reflector 4 and return to the right and augment the waves which go initially to the right. The member 6I63 is supported through the insulator 4" by the reflector 4-4, and the member 62-64 is supported by one or a few radial wires or rods 66 which are of considerable resistance and therefore do not interfere substantially with the waves, even though the lines of force have components in their direction. These wires or rods 66 carry the charging currents for the member 6264. The oscillatory discharge between the members 63 and 64 has a certain natural period and the reflector 4 is adjusted so that the reflected waves will be in phase with the waves that go directly to the right.

Fig. 20 shows a spark gap system adapted for the generation and propagation of the same type asymmetric electric waves.

and in cross-section at Fig, 22 may be employed.

Associated respectively with the spark gap knobs i3 and 84' are the solid D-shaped'conductor bodies 16 and 11. The lines of electric force between these bodies 16 and II will correspond to the lines of electric force shown in Fig. 30. for

with a proper adjustment of the reflector 34 the waves will be enhanced at the natural frequency of the oscillating system and the lines of force will be detached from'theb shaped electrodes and will be propagated to the right as asymmetric electric waves. They may be purified by a sieve 2| like that shown at 2| in Figs. 9a and 10.

An electrode system for generating asymmetric magnetic waves from spark discharges is shown in longitudinal section in Fig. 23 and in crosssection, in Fig. 24. The metal half cylinders 80 and II are insulated from the shell 3 and conductively connected to the respective spark discharge knobs 63" and 64". During the discharge oscillations the current paths in the conductor system at a given instant will be as indicated by the arrows in Fig. 24. A reflector 34 will be employed as shown in Fig. 23. Asymmetric magnetic waves will be thrown off right and left; those to the left in Fig. 23 will be reflected and will come back tothe spark gap. The reflector 34 will be properly adjusted so that the returning waves will enhance the outgoing waves and the radiation to the right will be of approximate asymmetric magnetic waves. These may be purifled by a sieve 2| like that shown in Fig. 18.

For the generation of symmetric magnetic waves, a system of electrodes and conductors such as shown in Figs. 25, 26 and 27 may be employed. Within the metallic sheath 3 is a figure-8 shaped frame carrying a pair of spark gap members 90 and SI with the axis of the gap across the axis of the guide. The insulation at 92 and 93 in the figure-8 frame interrupts a conductive path between the members 90 and 9| for direct currents, but permits a path for high frequency alternating currents. The conductors-adjacent to either such insulating body 92 or 93 may be regarded as the plates of a condenser. The oscillatory discharge currents flow along the members of the figure-8 frame as indicated by the arrows in Fig. 27,- charging and discharging the condensers at 82 and 93, and generating symmetric magnetic waves. Adjacent to the discharge knobs 90 and 9|, the currents in the figure-8 frame flow in opposite directions on opposite sides of the .gap, thus producing a null effect in the region, so far as those currents are concemed. Symmetric magnetic waves are radiated to'right and left, viewing the apparatus as in Fig. 25. On one side, these waves are reflected at 34 and returned to enhance the waves on the other side. The electric lines of force'of these waves being circumferential, they may be purified by the sieve 94 on the right having radial wires.

In all of Figs. 19 to 27, ordinary open air gaps are shown by way of example. They may be electron discharge devices within a considerable variety of choice. For spark discharges the knobs may be of zinc in air at various pressures or men, or a mercury spark with an atmosphere of hydrogen may be provided. In any case the oscillatory movements of the electrons are along paths which conform to lines of force of the desired waves, and those waves may be regarded as being produced comparatively directly from the oscillatory electrons. It is obvious that the adjustable iris shown by 49 in Figs. 11 and 24 above may also be used in connection with other sources of waves shown. Such a device not only controls the volume but it may be so used as to more clearly define the frequency of oscillation. I

In the appended claims, "transverse means transverse to the axis of the wave-guiding structure or to the direction of wave propagation.

I claim:

1. In combination, a wave guide consisting essentially of a metallic pipe and means for generating within said pipe for propagation therethrough an electromagnetic wave having a certain characteristic electric field pattern-and a frequency higher than a cut-off frequency de- I -pendent on a transverse dimension of said pipe,

' substantial component of motion along lines corrfiesponding to the lines of force of said electric eld.

2. The method of launching dielectrically guided waves in a wave guide comprising a gaseous dielectric medium and metallic means defining the periphery thereof, which comprises projecting free electrons within said medium and subjecting said electrons to an equilibrium field so directed as to cause said electrons to oscillate along paths conforming with the lines of electric force of said dielectrically guided waves.

3. In combination, a dielectric guide, a source of free electrons within said guide, means for causing said free electrons to oscillate and means for constraining the oscillations of said electrons to such paths that there are generated in and propagated through said dielectric guide, electromagnetic waves characterized in that they are readily transmitted through said guide only at frequencies above a critical frequency functionally related to the transverse dimensions of said guide. I

4. In combination with a wave guide comprising a metallic pipe enclosing-a gaseous dielectric medium, means for launching dielectrically guided waves in said pipe comprising an electron emitting cathode therein, a corresponding anode, and means comprising a third electrode to establish an equilibrium position for electrons emitted from said cathode, said electrons being caused to oscillate about said equilibrium position in such manner that the waves in the lines of force extending through said dielectric medium from said electrons substantially conform with a type of dielectrically guided waves.

5. In combination, a dielectric guide, walls enclosing a vacuum chamber within said guide, means to establish an electron discharge within said chamber, and a reflector across said guide, one way from said chamber, whereby the electron discharge will fluctuate at a period determined by the period of wave travel from the place of the discharge to the said reflector back.

and

s. In combination, a metal sheathed dielectric guide, walls enclosing'a coaxial vacuum chamber within the guide, a cathode and a grid and a plate electrode all. coaxially placed in said chamthe guide, an inner coaxial member extending one way from the chamber and- -forming a coaxial conductor system with the metal sheath of the guide, anannular reflector between the metal sheath and said member, and means to establish an electron discharge within said chamber, said reflector being adjusted so that concentric conductor system waves thereto will return at the proper period to enforce fluctuations of the discharge in said chamber, whereby dielectric displacement waves in the guide will be radiated the opposite way from the reflector.

8. In combination, a dielectric guide, means to establish a transverse electron discharge within said guide whereby any irregularity of the discharge will propagate a wave both ways along the guide, and a reflector on one side to return such wave and thereby establish a regular fluctuation of the discharge at the period of the to-and-fro waves, whereby there will be sustained radiation of waves the other way along the guide from the reflector.

9. In combination, a dielectric guide, means to establish an electron discharge within said guide with the electron paths directed along desired lines of electric force of a particular type of dielectrically guided waves to be generated, and means to make the electron discharge fluctuate in amplitude in regular periods, whereby such waves will be generated and propagated along the guide.

10. In combination, a metal sheathed dielectric guide, walls enclosing a gas-tight chamber within the guide, coaxial electrodes within and coaxial with the said chamber, and means to establish a fluctuating discharge symmetric with respect to the axis of the guide and in energy transfer relation with waves of symmetric type propagated along the guide.

11. In combination, a dielectric guide, and means for generating asymmetric waves within said guide for propagation therethroughcomprising means to establish anelectron discharge within the guide with the electron paths principally across a plane of symmetry of the guide and means to cause a fluctuation in the intensity of the discharge in these paths.

12. In combination, a dielectric guide, walls enclosing a chamber within the guide, means within the chamber to produce an electron discharge with the electron paths in large part directed across a plane of symmetry of the guide, and means to produce regular amplitude fluctuations of the discharge current, whereby asymmetric electric waves will be generated and propagated along the guide.

13. In combination, a dielectric guide, an electron emitting cathode in the axis of the guide,

means to generate a magnetostatic fleld directed along the axis, and means to produce regular periodic fluctuations in the discharge from said cathode whereby electromagnetic waves will be generated and propagated along the guide, said waves having a substantial component of sym-' 15. In combination, a die lectric,guide.-.a Pa

of spark discharge members within the guide, means to maintain repeated discharges, and a reflector across the guide one way from said members, whereby dielectric displacement waves will be generated and propagated the other way along the guide.

16. In combination, a metal sheathed dielectric guide, two spark discharge members within said guide having their axis across the axis 0! the guide, and a reflector one way therefrom across the guide, waves occasioned bya discharge across said members being reflected and propagated the opposite way with a substantially definite frequency as dielectric displacement current waves within the guide.

17. In combination, a metal sheathed dielectric guide, spark gap members within said guide having their axis transverse to the axis of said guide,

and means to energize them and thereby generate and propagate asymmetric type waves along the guide.

18. In combination, a wave guide consisting essentially of a metallic pipe, means for generating and propagating through said pipe electromagnetic waves characterized by the existence of a cut-oil frequency dependent on a transverse dimension of said pipe, said generating means comprising a pair of electrodes and means for maintaining an oscillatory discharge between them, said electrodes being disposed with their axis conforming in direction with electric lines of force in said electromagnetic waves.

19. In combination, a wave guide comprising a metallic pipe containing only a dielectric medium, a pair of elongated electrodes disposed lengthwise within said pipe at one end thereof, means for establishing an oscillatory spark discharge between iuxtaposed localized parts of said electrodes, and reflecting means closing said end oi the pipe, said electrodes and reflecting means being so spaced as to enhance the oscillatory discharge at the natural frequency of the electrode system.

20. A combination in accordance with the claim next preceding in which said electrodes are of such cross-section and so disposed transversely of said guide that asymmetric electric waves are produced and propagated through said guide.

21. In combination, a wave guide comprising a metallic pipe containing a dielectric medium and carrying therein high frequency electro-' magnetic waves having a certain characteristic electric fleld pattern such that the guide presents to said waves the characteristic of a highpass fllter, and a translating device comprising means for producing free electrons within said pipe and means for impelling said electrons to oscillate with a substantial component of motion along lines corresponding to the lines of force of said electric field.

22. In combination, a uni-conductor wave guide comprising a metallic pipe containing a gaseous dielectric medium and carrying therein electromagnetic waves characterized by the existence of a cut-oil frequency functionally related to a transverse dimension of said pipe, and a translating device within said guide comprising a pair of electrodes and means for maintaining an oscillatory discharge between them, said electrodes being so disposed that said discharge substantially conforms in direction with electric lines of force in said electromagnetic waves.

23. In combination with a wave guide comprising a metallic pipe for the transmission therein of electromagnetic waves having such characteristic field patterns that they are transmitted only at frequencies above a critical frequency, a discharge device in energy transfer relation with said waves comprising a plurality of electrodes that are coaxial with each other and with said pipe and one of which is in substantial continuation of said pipe.

24. In combination, a wave guide comprising a metallic pipe containing a gaseous dielectric medium and carrying dielectricaliy guided waves therein, and a translating device for launching or receiving said waves comprising cathode, grid and plateelectrodes that are coaxial with each other and with said pipe, said cathode and grid electrodes being disposed within said pipe.

25. In combination, a wave guide comprising a gas-filled metallic pipe carrying dielectricaliy guided waves of symmetrictype, a portion of said pipe being of reduced cross-section, and a discharge device comprising a plurality of coaxial electrodes disposed in said portion of pipe and coaxial therewith for generating or receiving said waves.

26. A combination in accordance with claim 25 in which one of said coaxial electrodes comprises said pipe.

2'7. In combination, a wave guide comprising a metallic pipe, an ultra-high frequency oscillation generator comprising a hollow electrode and at least one other electrode within said hollow electrode, and a metallically bounded chamber, one end of said hollow electrode opening into said chamber and the other end into said pipe, the only dielectric path between said chamber andsaid pipe being through the interior of said hollow electrode.

28. A combination in accordance with claim 27 in which said pipe, electrodes and chamber are coaxial with each other.

29. A hollow metallic pipe for the transmission of dielectricaliy guided waves and an electronic oscillation generator adapted for operation at a frequency of the order of a billion cycles per second, said oscillation generator comprising a hollow electrode of comparatively small crosssection coaxial with said pipe and metallically continuous therewith and another electrode within said hollow electrode, said electrodes being so constructed and arranged as to establish an energy transfer relation between said dielectrically guided waves and said oscillation generator.

GEORGE C. SOUTHWORTH. 

